Radiation detectors which utilize thermopiles to detect the heat flux from target surfaces have been used in various applications. In some applications, an indication of the temperature of the target surface is provided as a function of the measured heat flux. Such radiation detectors have been used by physicians to scan patients to note regions of elevated temperature. An injury results in increased blood flow which in turn results in a higher surface temperature.
Often it is the difference between different surface areas which is of interest. For example, when one limb is injured, another limb may be scanned to provide a reference temperature. The difference between that reference temperature and the temperature of the surface area over the injury is indicative of the extent of the injury.